<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>canvas绘制选框</title>
    <style>
        canvas {
            position: absolute;
            left: 0;
            top: 0;
            background: #000;
            width: 100%;
            height: 100%;
        }
    </style>
    <script src="../common.js"></script>
</head>
<body>
    <canvas id="canvas"></canvas>
    <script src="./index.js"></script>
</body>
</html>